In the past, needle iron oxide was most commonly used among powder magnetic materials for magnetic recording media.
Magnetic recording media are currently required to have a higher signal recording density as represented by the widespread use of home VCRs and the development of high performance audio cassette tape, video tape, computer tape, magnetic disks, floppy disks, magnetic cards and the like. The requirement of higher density magnetic recording could not be met by the conventional needle iron oxide, and a variety of magnetic materials having higher coercivity and magnetic flux density have been developed.
One class of advanced magnetic powder materials includes metallic magnetic powders based on magnetic metals which have been commercially utilized in high performance audio cassette tape, video tape, DAT tape, magnetic disks and the like. It is still desired to further improve the output and S/N or C/N of magnetic recording media of the coating type using metallic magnetic powders. To this end, it is desired to increase the residual magnetic flux density, i.e. remanence Br of media, which in turn, requires to increase the saturation magnetization .sigma.s of magnetic powder.